History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

Journal Article · Fri Sep 08 00:00:00 EDT 2006 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2356389· OSTI ID:20888210

Williamson, Jeffrey F ^[1]

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1. Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298 (United States)

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

• OSTI ID: 20888210
• Journal Information: AIP Conference Proceedings, Vol. 854, Issue 1; Conference: 9. Mexican symposium on medical physics, Guadalajara, Jal. (Mexico), 18-21 Mar 2006; Other Information: DOI: 10.1063/1.2356389; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BIOLOGICAL RADIATION EFFECTS
BRACHYTHERAPY
CESIUM 137
COBALT 60
DOSIMETRY
ERYTHEMA
GAMMA RADIATION
IODINE 125
IRIDIUM 192
K CAPTURE
MONTE CARLO METHOD
PALLADIUM 103
POINT SOURCES
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSE UNITS
RADIATION SOURCE IMPLANTS
RADIUM 226
RADON 222
SPECIFICATIONS
STANDARDIZATION